Radio receiver



y 2, 1944- J. A. VAN LIESHOUT I 2,347,977

RADIO RECEIVER Filed May 25, 1942 LF AMPLIFIER 'vnvvvvvvv g 20/ z zozsws JAVANLIESHOUZ INVEN TOR.

ATTORNEY Patented May 2, 1944 UNITED STATES ,RADIO RECEIVER Application May 25, 1942, Serial No. 444,408

19 Claims.

The present invention relates to improvements in radio receivers, and more particularly to a device for simultaneously indicating visuallyallthe important operating conditions of a radio receiver.

It is an object of the invention to provide a non-mechanical tuning .dial for a multi-band radio receiver whereby the frequency band and the frequency to which the radio receiver is tuned is indicated visually without the use of a dialdrive or similar mechanical expedients.

Another object of the invention is to provide a novel arran ement for simultaneouslyindicating visually, the frequency band and the frequency to which a radio receiver is tuned, whether the receiver is properly tuned, and the intensityof the incoming signal currents.

In some instances it is necessary to make a recording of the program materialreceived. In .such cases, to obtain a satisfactory recording, it is essential that the radio receiver be accurately tuned and at the sametime the intensity of the program material (theaudio intensity) be .kept within specified limits.

It is therefore a further object of the invention o P ovide. a nove ar an ment b v which th t i y of th progra materia isindiqat d vi ually simultaneously with the above reierred p rat c t n .Of th radio. rece ver- Astill further object of .the invention is to provide a tuning i d c to whic is emeientand liable inoperation and which ca n be assembled in a radio receiverin asi nple manner.

These and further. objects of the invention will appear. asthespecification progresses.

In accordance With theinvention use is made of a cathode-ray type tube wherein the conditions to be indicated are simultaneously manifested by characteristic displacements and/or variations in the intensity of the electron beam impinging on the screen of thetube. .More specifically,- by applying suitable voltagesderivedirom the radio receiver, the electron beam of the cathode-ray tube is made to deflect in a, vertical direction to predetermined positions corresponding to the t ni g band t hic he, ece r a ust and. to. deflect in a horizontal direction corresponding to the frequency to which the receiver is tuned. Furthermore, by. controllingthevertical and horizontal size of the image entire screen of the cathode-ray tnbe, the intensity .of e si n li curr nt andit e ntehsity 9 th am m e ial i im taneousl ndicated- 'he'inv nt on willgbe de t ibe in sreaierd tail with reference --to the appended drawing forming part of the specification and in which:

Figure 1 is a frontal view of .aradio receiver embodying thevisual indicating deviceof the in- .vention.

Fig. 2 is a circuit diagram-schematically illustrating the visual indicator of the invention in its use in a radio receiver.

Fig. 3 is a side View partly in cross-section showing .a method of controlling the .efiectiver ness of the visual indicator in accordance Witha further feature of the invention.

Fig. ,4 illustrates a modified arrangement for controlling the efiectivenes of the visual indicator during stand by periods.

Referring to Fig. 1, the radio receiver shown comprises as a visual indicatona cathode-ray tube, the fluorescent ,screenor which is covered with a transparent scale having markings corresponding to the tuning bandsandirequencies to which the receiver is adapted to be tuned. The

ti cally and horizontally mindicete respectiv l the intensity of the signalling currents and the intensity or the program (audio) material. Thes displacements and/or variationsof the. electron beamin accordance With the preierred embodiment of the invention have been indicated in Fig. 1 by suitable legends.

The circuit arrangementshown Fig. 2 illustrates one method by which control voltages may be derived-from a radio receiverfor deflecting the electron beam of the cathode -ray tube tov produce the visual indications above set' forth. :The circuit illustrated (sh own partly in block iorm and with non-pertinent portions omitted for purposes of simplification) is for a. multi-band superheterodyne receiver.

The signal currents received, for example, by an antenna I00, are applied to the tuning circuit of a radio frequency amplifier-converter H! which includes inductancesi2'd, 2b, lzc i 2 1 and uency I2e each inductance corresponding toa band of the l receiver, and an adjiistabl'e tuning condenser I l for tuning the receiver through each frequency band. The inductances I2 are selectively placed in circuit by a switch 13 operated by the band-change knob of the receiver. Similarly condenser II is adjusted through its range by a suitable tuning knob.

Within the amplifier-converter I the signal currents are heterodyned with a locally generated oscillation derived from a variable frequency oscillator which similarly comprises inductances IBa, I61), I60, I6d and I 66 corresponding to the tuning bands of the receiver and an adjustable tuning condenser I5 for adjusting the oscillator frequency through its tuning range. A switch II ganged to the switch I3, selectively places the inductances I6 in circuit. Similarly, and in ac cordance with known practice, the condenser I5 is ganged to and is simultaneously adjusted with the condenser II.

The heterodyned signal voltage derived from the amplifier-converter I0 is supplied through an intermediate frequency (I. F.) fixed tuned amplifler I8 to a transformer 20 having its primary winding 2| connected across the output of the I. F. amplifier and its secondary 22 connected to a demodulator circuit for deriving the program material from the signal currents. Semi-adjustablecondensers 23 and 24 are connected across the primary and the secondary windings respectively of the transformer 20 to tune these'winding to the I. F. frequency. The demodulation of the signal currents is effected by a diode rectifier I9 connected across the secondary 22 of the transformer 20 with the interposition of a load resistor25. A condenser 26 shunts the resistor 25 for filtering the I. F. components from the output'voltage of the demodulator. As shown the resistor 25is of the potentiometer type and thereby s'ervesas a volume control for the receiver, the audio voltages being obtained from an adjustable tapping of the potentiometer and are supplied to a suitable amplifier and loud-speaker jarrangement (not shown).

I 'For'the visual indication of the tuning band, tuning frequency, signal intensity and audio intensity, I provide a cathode ray tube 36 comprising an envelope 3|, a cathode 32 serving as a source of the electron beam, a cathode heater 33,

a control grid 34, and focussing electrodes 35 and 35.". For deflecting the electron' beam in a horizontal direction there are provided horizontal deflecting electrodes 31 and 38, and for controlling the path of the electron stream in a vertical direction, vertica1 deflecting electrodes 39 and 40.

The direct current voltage supply for the tube may be derived from a potentiometer 4i connecte'd'to a suitable voltage source (not shown) and comprising individual resistor elements 42, 43', 44,

45, 46 and 41 connected in series. As shown, de-

flecting plates 31 and 39 are connected to the positive end of resistor 42 and are maintained at ground potential with respect to the other electrodes or the tube by being connected to the chassis of the radio receiver. 7 Focussing electrode 35 is connected to the junction of resistors 43Zand 44, focussing electrode 36 is connected to the junction oi resistors 42 and 43 and cathode 32 is connected to the junction of resistors 44 and 45. y 7 y Connections are provided at the junction of resistors 45- 46 a nd 46-41 for purposes later to b' mq e lvm nt o -,4

In accordancewith the embodiment shown in Fig.2 the cathode-ray tube 30 is made to indicate the frequency band and the tuning frequency of t dio e e v b app yin to t deflectin electrodes 31-38 and 3340 voltages proportional to these operating conditions of the radio receiver. The voltage for deflecting the electron beam vertically and thereby indicating the frequency band of the receiver, is obtained from a resistor 50 connected to a suitable voltage source (not shown). Resistor 50 is grounded at its electrical center and is provided with tappings corresponding in number to the number of the frequency bands of the receiver. By means of a switch 5| the deflecting electrode 40 is selectively connected to the tappings of resistor 50 and is made to assume predetermined voltage differences relative to electrode 39. In practice the switch 5I is ganged to the band-change switches I3and I! and the vertical deflection of the electron beam is simultaneously effected by the bandchange knob of the receiver.

The voltage for deflecting the electron beam in a horizontal direction to thereby indicate the tuning frequency of the receiver, is obtained from a potentiometer I50 connected to a suitable voltage source (not shown) and grounded at its electrical center. By varying the position of the arm I5I of the potentiometer simultaneously with the tuning condensers II and I5 by means of a common control, a progressively negative or positive potential is applied to the deflecting electrode 38 relative to the electrode 31 causing the beam to move in a continuous manner across the screen of the cathode-ray tube.

FOr indicating the intensity of the signal source and the proper tuningof the receiver, a voltage proportional to the I. F. voltage is applied to the vertical deflecting electrode relative to the electrode 39, said voltage being derived from a connection to the high-potential side of the primary 2I of I. F. transformer 20 and being applied to electrode 40 through an isolating condenser I53. A resistor I54 is connected in the lead between the electrode 40 and the arm of switch BI and serves to prevent short-circuiting of the I. F. voltage to ground through the resistor 50. As will readily appear, the I. F. voltage appearing at the input to the transformer 20 is proportional to both the signal strength of the signal current and the proper tuning of the receiver and these operating conditions are indicated by the length of the vertical line traced by the electron beam on the screenof the cathode-ray tube whereby the longer the line the greater the signal strength and/or the more correct the tuning of the receiver.

' For indicating the intensity of the audio output of the receiver a voltage proportional to the audio voltage is applied to the horizontal deflecttive during stand-by periods i. e. during periods when observation of the operating conditions of the receiver is unnecessary.' More particularly,

during periods of observation a control voltage of relatively low negative value with respect to the cathode 32 is applied to the control grid 34. During stand-by periods a control grid voltage or relatively large negativevalue relative. to the cathode is applied tolthe grid thereby eflectivcly blanketin the electron beam or at least greatly diminishing its intensity during such stand-by periods. For this purpose the control grid 34 isv selectively connected to one or the other of the junctions between resistors 45-46 and 40-41 by a switch I10.

Switch I10 may comprise (see Fig. 3) fixed contact members 200 and 29! connected to the junction of the resistors 45-46 and 4fi47 and a movable switch arm 282 connected to the control grid 34. As shown, arm 262 is pivoted at 203 and at its driven end is provided with a yoke 2M.

Switch I10 is actuated by axial displacement of the tuning knob 2) of the radio receiver said displacement being transmitted to the switch by a shaft 209 to which the knob is afiixed and a collar 205 positioned on the shaft and engaging the yoke 204.

In operation, the switch is normally maintained in the stand-by position at which time the arm 202 is connected to contact 208 and the electron beam is blanketed by the relatively large negative voltage so applied to the control grid 34 of the cathode-ray tube from the junction of resistors 46-41.

To apply a relatively low negative potential to the control grid during the tuning periods, the arm 262 is connected to contact 21H said connection being effected by axially displacing the tuning knob simultaneously with the rotation thereof incidental to the tuning operation.

For maintaining the switch in its normal stand-by position there is provided on shaft 239 a compression spring 2 one end of which abuts against a fixed support 2l2 secured to the chassis of the radio receiver and the other end of which abuts against a collar 2l3 provided on the shaft.

Shaft 209 is formed with an annular groove 2 i 6, within which is retained a driving cord M5 for actuating the tuning condensers H and I5 and the potentiometer I59.

In Fig. 4 there is shown another method of making the cathode-ray tube effective during tuning periods and ineifective during stand-by periods. In the method shown in Fig, 4 an oscillator supplies a negative voltage to the control grid of the cathode-ray tube during stand-by periods thereby blanketing the electron beam during such periods. The oscillator shown comprises a discharge tube 249 having an anode 258, a cathode 25! and a grid electrode 252 connected in feed-back relationship to a fixed tuned resonance circuit, comprising an inductance 253 and a condenser 254. A grid leak 255 shunted by a grid condenser 250 is connected in series with the tuning inductance and the grid electrode 252 and provides the normal operating negative bias voltage of the oscillator which bias voltage is applied to the control grid 36 of the cathode-ray tube through a resistance-capacity filter 256-257. Connected to the high potential side of the resonance circuit 253254 is a metal knob 25l serving for the tuning of the radio receiver.

The operation of the control system shown in Fig. 4 is as follows:

During stand-by periods, the oscillator developes a relatively large negative voltage at the grid 252. This voltage is applied to the control grid 34 thereby blanketing the electron beam of the cathode-ray tube. However, when the tuning knob 26! is grasped incidental to adjusting the frequency of the radio receiver, the hand capacity so introduced, so loads the oscillator that it ceases operation. Immediately thereupon, the negative voltage developed at thev grid 25-2 is diminished andconsequently the negative voltage applied to the control-grid 34 is also diminished thereby permitting a greater intensity of the electron beam of the cathode-ray tube. When the receiver has been tuned properly to the desired frequency and the tuning knob. is released, the oscillator is again made operative and a large negative voltage is again applied to the control grid of the cathoderay tuning indicator.

While I have described my invention in a specific embodiment and by a specific example, I do not wish to be limited thereto for obvious modification will appear to those skilled in the art without departing from the spirit and scope of the invention.

What I claim is:

A visual indicating system for a multi-band radio receiver, comprising a cathode-ray tube having a fluorescent screen, and. electron beam producing elements, means todeflect the electron beam along one axis of the fluorescent screen in incremental steps corresponding to the tuning bands of the radio receiver and means to deflect the electron beam along an axis perpendicular to said first axis in an amount corresponding to the tuning frequency of the radio receiver, said first means being actuated simultaneously with means to change the tuning band of the receiver and said second means being actuated simultaneously with means to tune the radio receiver through its frequency bands.

2. A visual indicating system for a multi-band radio receiver, comprising a cathode-ray tube having a fluorescent screen, an electron beam producing elements, and deflecting electrodes for defleeting the beam in a vertical and horizontal manner, a voltage source connected to the vertical deflecting electrodes and a voltage source connected to the horizontal deflecting electrodes,

means to vary the voltage applied to the vertical deflecting electrodes in an incremental manner to deflect the electron beam along thev vertical axis of the fluorescent screen in incremental steps corresponding to the tuning bands of the radio receiver, and means to vary the voltage applied to the horizontal deflecting electrodes in a continuous manner to deflect the electron beam along the horizontal'axis of the fluorescent screen in a continuous manner, said first voltage varying means being actuated simultaneously with means to change the tuning band of the receiver and said second voltage varying means being actuated simultaneously withmeans to tune the radio receiver through its frequency bands.

3. A visual indicating system for a multi-band radio receiver, comprising a cathode-ray tube having a fluorescent screen, an electron beam producing elements and deflecting electrodes for deflecting the beam in a vertical and horizontal manner, a voltage source connected to the vertical deflecting electrodes and a voltage source connected to the horizontal deflecting electrodes, means actuated simultaneously with means to change the tuning band of the receiver to vary the voltage applied to the vertical deflecting electrodes in an incremental manner to deflect the electron beam along the vertical axis of the fluorescent screen in incremental steps corresponding to the tuning bands of the radio receiver, means actuated simultaneously vwth means to tune the radio receiver through its frequency bands to vary the voltage applied to the horizontal deflecting electrodes in a continuous manner to deflect the electron beam along the horizontal axis of the fluorescent screen in a continuous manner, and means to superimpose on one of said deflecting voltages a voltage proportional to the amplitude of the signalling currents of the radio receiver. 7

4. A visual indicating system for a multi-band radio receiver, comprising a cathode-ray tube having a fluorescent screen, an electron beam producing elements and deflecting electrodes for deflecting the beam in a vertical and horizontal manner, a voltagesource connected to the vertical deflecting electrode and a voltage source connected'to the horizontal deflecting electrodes, means actuated simultaneously with means to change the tuning band of the receiver to vary the voltage applied to the vertical deflecting electrode in an incremental manner to deflect the electron beam along the vertical axis of the fluorescent' screen in incremental steps corresponding to the tuning bands of the radio receiver, means actuated simultaneously with means to tune the radio receiver through its frequency bands to vary the voltage applied to the horizontal deflecting electrodes in a continuous manner to deflect the electron beam along the horizontal axis of the fluorescent screen in a continuous manner, means to superimpose on the vertical deflecting voltage a voltage proportional to the amplitude of the signalling currents of the radio receiver, and means to superimpose on the horizontal deflecting voltage a voltage proportional to the audible output of the radio receiver.

5. A visual indicating system for a multi-band radio receiver, comprising a cathode-ray tube having a fluorescent screen, an electron beam producing elements and at least two pairs of relatively perpendicular deflecting elements, means actuated simultaneously with means to change the tuning band of the receiver for deflecting the electron beam along one axis of the fluorescent screen in incremental steps corresponding to the tuning bands of the radio receiver, means actuated simultaneously with means to tune the radio receiver through its frequency bands for deflecting the electron beam along an axis perpendicular to said first axis in an amount corresponding to the tuning frequency of the radio receiver, and means for selectively blanketing the electron beam during stand-by periods and rendering the system substantially ineffective during said periods.

6. A visual indicating system for a multi-band radio receiver, comprising a cathode-ray tube having a fluorescent screen, an electron beam producing elements, a control grid for the electron beam and relatively perpendicular deflecting elements, means actuated simultaneously with means to change the tuning band of the receiver for deflecting the electron beam along one axis of the fluorescent screen in incremental steps corresponding to the tuning bands of the radio receiver, means actuated simultaneously with means to tune the radio receiver through its frequency bands for deflecting the electron beam along an axis perpendicular to said first axis in an amount corresponding to the tunin frequency of the radio receiver, a voltage source for applying a substantially large negative potential to saidcontrol grid to selectively blanket the electron beam during stand-by periods, and means actuated by the tuning member of the radio receiver to diminish the negative potential of the voltage applied to the control grid during tuning periods of the radio receiver.

7. In the method of the operating a visual indicating system for visually indicating operating conditions of a radio receiver by means of a cathod ray tube, selectively making the system effective during tuning periods of the radio receiver and blanketing the electron beam of the cathoderay tube during stand-by periods.

8. In a visual indicating system for visually indicating operating conditions of a radio receiver by means of a cathode-ray tube having an electron beam producing elements, a control electrode for the electron beam and relativeli perpendicular deflecting elements, a voltage source, a switch member actuated simultaneously with means to tune the radio receiver through its tuning bands, said switch member selectively applying a relatively high negative potential from the voltage source to the control electrode in its non-actuated position and applying a substantially low negative potential to the control electrode in its actuated position.

9. In a visual indicating system for visually indicating operating conditions of a radio receiver by means of a cathode-ray tube having electron beam producing elements, a control grid and relatively perpendicular deflecting elements, means to selectively make the system effective during tuning periods of the radio receiver and to blanket the electron beam during stand-by periods, said means comprising a source of oscillations including means to develop a substantially high negative voltage, means to apply the negative voltage to the control grid of the oathode-ray tube, and means associated with means for tuning the radio to render said source of oscillations inoperative during tuning periods.

. LOISIUS J. A. VA'N LIESHOUT. 

